This invention relates to display devices, and more particularly to getters used in field emission displays (FEDs).
In a typical FED, a cathode has a plurality of conical emitters that addressably and controllably emit electrons, and an anode has a transparent dielectric layer, a transparent conductive layer over the dielectric layer, a grille formed over the conductive layer to define pixel regions, and a phosphor coating applied to the conductive layer in the defined pixel regions. When activated, the emitters emit electrons to the pixel regions, to produce a visible light image. The light at each pixel is controlled by the current in the emitters facing the respective pixel.
The cathode and anode are assembled very close together, e.g., about 200-250 microns, in a package with a vacuum seal, such as a frit glass seal, at or near the perimeter of the anode and cathode. In the small space between the anode and cathode, any residual gases or molecules can cause arcing or shorting. To address this problem, a getter is placed in the display package and is then activated to sorb free molecules. Placement of the getter is problematic, however, because of the small space. In some FEDs, the cathode is mounted between the anode (also referred to as a faceplate) and a backplate; in this case, a getter can be placed in the space between the cathode and the backplate. While saving space, such placement puts the getter away from the space between the cathode and anode where gettering is needed most. In other cases, the getter is placed on the side of the cathode and anode, but such placement increases the width of the display without increasing the screen size.
The present invention includes a display with two parallel plates and a getter that is well-positioned between the plates for gettering molecules without adversely affecting the size of the display.
According to one aspect of the present invention, a display has an anode with a substrate and a grille formed on the substrate and made at least in part of a getter material. The grille defines a plurality of pixel regions that are coated with phosphor before the display is assembled and vacuum sealed. After the display is sealed or during sealing, the getter is subjected to energy that activates the getter without causing other portions of the display to exceed their respective breakdown temperatures. The process of applying the getter can be performed with masking and etching techniques. The display is preferably an FED having a cathode that has a plurality of conical emitters for emitting electrons to the pixel regions. The anode assembled and vacuum sealed with the cathode so they are parallel to each other.
According to another aspect of the present invention, a display has a grille on a substrate to define pixel regions to be coated with phosphor, and a getter material formed over at least a portion of the grille but not over the defined regions. The getter can be formed over the entire grille or only over selected rows and/or columns of the grille. The getter can be formed directly on the grille, or over the grille but directly on an intermediate conductive layer.
By making the grille at least in part out of a getter material, a getter is provided at a useful location for gettering, ie., between the anode and the cathode. Because the getter is serving both a getter function and a grille function, the getter does not require additional space or an additional number of components over a display without a getter. The display can therefore omit the need for an additional getter. If the getter material is put over the grille, it provides gettering without adding to the width of the device. Other features and advantages will become apparent from the following detailed description, drawings, and claims.